The Molecular Epidemiology in Children's Environmental Health (MECEH) Training Program began July, 2001 and is in its fourteenth training year. MECEH is defined as the use of biological, molecular and biostatistical measures in epidemiological research to determine how environmental exposures impact children's health at the physiologic, behavioral, cellular, and molecular levels. The marriage of epidemiology, medicine, statistical genetics, molecular biology, molecular genetics, and molecular epidemiology serves as an umbrella for focused research in genetic and biomarker environmental epidemiology. MECEH has 3 main participating departments: Environmental Health, Pediatrics, and Molecular Genetics. MECEH has had a continuous full enrollment with 21 pre-doctoral and 36 postdoctoral fellows trained or in progress, including 27 MD/DO fellows. Trainees have made great professional strides with national presentations, numerous publications, grant submissions and obtaining academic, government and industrial research positions. This application requests support for four pre-doctoral and six postdoctoral positions each year for 2016-2021 which will maintain its current size. The MECEH's long term objective is to continue increasing the number of cross-trained epidemiologists, physician epidemiologists, biostatisticians, and molecular biologists who investigate high impact issues related to environmental exposures and complex childhood diseases. The overarching rationale for this training program has been stated in such federal initiatives as the Children's Health Act of 2000 (HR 4365) which stressed investment in tomorrow's pediatric researchers (sec 1002). The MECEH has three primary goals: 1) provide a strong grounding in epidemiologic, biostatistical, and wet and dry laboratory molecular methods, 2) prepare students for interdisciplinary research and enhance clinical research workforce training as stated in the NIH roadmap, and 3) in concert with Francis Collins' direction for opportunities and challenges MECEH seeks to expand growth areas for trainee expertise in statistical genomics, epigenetic epidemiology, and design of community based participatory research. These goals are achieved through the recruitment of high quality applicants, including underrepresented minorities, mentorship by a core of nationally- and internationally-renowned teacher-scientists, support by research-intensive environmental health, pediatric, and molecular genetics departments, well-funded scientific programs and centers, and advice from a distinguished and enthusiastic External Advisory Board.